Remove AsyncError with Expando.

pkg/scheduled_test/lib/src/scheduled_server/safe_http_server.dart

Index: pkg/scheduled_test/lib/src/scheduled_server/safe_http_server.dart
diff --git a/pkg/scheduled_test/lib/src/scheduled_server/safe_http_server.dart b/pkg/scheduled_test/lib/src/scheduled_server/safe_http_server.dart
index 7ece341d06a8d52bc7557c9cf293fca0d159886b..2e5b9cc49afab7bd82a838244f11153ad0eed142 100644
--- a/pkg/scheduled_test/lib/src/scheduled_server/safe_http_server.dart
+++ b/pkg/scheduled_test/lib/src/scheduled_server/safe_http_server.dart
@@ -42,13 +42,12 @@ class SafeHttpServer extends StreamView<HttpRequest> implements HttpServer {
   HttpConnectionsInfo connectionsInfo() => _inner.connectionsInfo();
 
   StreamSubscription<HttpRequest> listen(void onData(HttpRequest value),
-      {void onError(AsyncError error), void onDone(),
+      {void onError(error), void onDone(),
       bool cancelOnError: false}) {
     var subscription;
     subscription = super.listen((request) {
       onData(new _HttpRequestWrapper(request));
-    }, onError: (e) {
-      var error = e.error;
+    }, onError: (error) {
       // Ignore socket error 104, which is caused by a request being cancelled
       // before it writes any headers. There's no reason to care about such
       // requests.